Shower head, vapor phase growth apparatus, and vapor phase growth method

ABSTRACT

A shower head according to an embodiment includes: a mixing chamber mixing a plurality of process gases; a shower plate provided below the mixing chamber, the shower plate including a plurality of longitudinal flow paths and a lateral cooling flow path provided between the longitudinal flow paths, a mixed gas of the process gases flowing through the longitudinal flow paths, a cooling medium flowing through the lateral cooling flow path; and an outer circumferential portion cooling flow path provided around the shower plate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Applications No. 2015-217593, filed on Nov. 5, 2015, theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a shower head that supplies processgas, and a vapor phase growth apparatus and a vapor phase growth methodusing the shower head.

BACKGROUND OF THE INVENTION

As a method for forming a high-quality semiconductor film, there is anepitaxial growth technique that forms a film on a substrate using vaporphase growth. In a vapor phase growth apparatus using the epitaxialgrowth technique, a substrate is placed on a supporter in the vaporphase growth apparatus which is maintained at normal pressure or reducedpressure. Then, process gas, which is raw material gas, is supplied tothe substrate while the substrate is being heated. For example, thethermal reaction of the process gas occurs in the surface of thesubstrate and an epitaxial single-crystal film is formed on the surfaceof the substrate.

If the process gas is supplied to the substrate, it is preferable touniformly supply the process gas onto the substrate, using a showerhead. Here, while a film is being formed, the temperature of the showerhead increases and the shower head is deformed. Therefore, a process ofcooling the shower head is performed.

SUMMARY OF THE INVENTION

A shower head according to an embodiment includes: a mixing chambermixing a plurality of process gases; a shower plate provided below themixing chamber, the shower plate including a plurality of longitudinalflow paths and a lateral cooling flow path provided between thelongitudinal flow paths, a mixed gas of the process gases flowingthrough the longitudinal flow paths, a cooling medium flowing throughthe lateral cooling flow path; and an outer circumferential portioncooling flow path provided around the shower plate.

A vapor phase growth apparatus according to an embodiment includes: areaction chamber; a supporter provided in the reaction chamber, asubstrate being capable of being placed on the supporter; and a showerhead provided in an upper part of the reaction chamber, the shower headincluding a mixing chamber mixing a plurality of process gases, a showerplate provided below the mixing chamber, the shower plate including aplurality of longitudinal flow paths and a lateral cooling flow pathprovided between the longitudinal flow paths, a mixed gas of the processgases flowing through the longitudinal flow paths, a cooling mediumflowing through the lateral cooling flow path, and an outercircumferential portion cooling flow path provided around the showerplate.

A vapor phase growth method according to an embodiment includes: mixinga plurality of process gases; supplying a mixed gas of the process gasesto a plurality of longitudinal flow paths provided in a shower plate;controlling a temperature of the shower plate using a lateral coolingflow path provided between the longitudinal flow paths and an outercircumferential portion cooling flow path provided around the showerplate, such that a difference between the temperature of an outermostcircumferential portion and the temperature of a central portion of theshower plate is equal to or less than 5° C., a cooling medium flowingthrough the lateral cooling flow path; supplying the process gases fromthe longitudinal flow paths to a reaction chamber; and growing a film ona substrate put into the reaction chamber using the process gases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating a mainportion of a vapor phase growth apparatus according to a firstembodiment;

FIG. 2 is a bottom view schematically illustrating a shower plate and anouter circumferential portion cooler of the vapor phase growth apparatusaccording to the first embodiment;

FIG. 3 is a bottom view schematically illustrating a shower plate and anouter circumferential portion cooler of a vapor phase growth apparatusaccording to another aspect of the first embodiment;

FIG. 4 is a flowchart illustrating a vapor phase growth method accordingto the first embodiment;

FIGS. 5A and 5B are diagrams illustrating the temperature distributionof a shower plate of the first embodiment;

FIGS. 6A to 6D are diagrams illustrating the characteristics of a filmformed by the vapor phase growth apparatus according to the firstembodiment;

FIG. 7 is a cross-sectional view schematically illustrating a mainportion of a vapor phase growth apparatus according to a secondembodiment;

FIG. 8 is a bottom view schematically illustrating a shower plate and anouter circumferential portion cooler of the vapor phase growth apparatusaccording to the second embodiment;

FIG. 9 is a bottom view schematically illustrating a shower plate and anouter circumferential portion cooler of a vapor phase growth apparatusaccording to another aspect of the second embodiment;

FIG. 10 is a bottom view schematically illustrating a shower plate andan outer circumferential portion cooler of a vapor phase growthapparatus according to another aspect of the second embodiment;

FIG. 11 is a bottom view schematically illustrating a shower plate andan outer circumferential portion cooler of a vapor phase growthapparatus according to a third embodiment; and

FIG. 12 is a flowchart illustrating a vapor phase growth methodaccording to a fourth embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the drawings.

In the specification, the direction of gravity in a state in which avapor phase growth apparatus is provided so as to form a film is definedas a “lower” direction and a direction opposite to the direction ofgravity is defined as an “upper” direction. Therefore, a “lower portion”or a “lower part” means a position in the direction of gravity relativeto the reference and a “lower side” means the direction of gravityrelative to the reference. In addition, an “upper portion” or an “upperpart” means a position in the direction opposite to the direction ofgravity relative to the reference and an “upper side” means thedirection opposite to the direction of gravity relative to thereference.

In the specification, “process gas” is a general term of gas used toform a film on a substrate. The concept of the “process gas” includes,for example, raw material gas, source gas, carrier gas, and separationgas.

First Embodiment

A shower head according to this embodiment includes a mixing chambermixing a plurality of process gases; a shower plate provided below themixing chamber, the shower plate including a plurality of longitudinalflow paths and a lateral cooling flow path provided between thelongitudinal flow paths, a mixed gas of the process gases flowingthrough the longitudinal flow paths, a cooling medium flowing throughthe lateral cooling flow path; and an outer circumferential portioncooling flow path provided around the shower plate.

FIG. 1 is a cross-sectional view schematically illustrating a mainportion of the vapor phase growth apparatus according to thisembodiment. FIG. 2 is a bottom view schematically illustrating a showerplate and an outer circumferential portion cooler of the vapor phasegrowth apparatus according to this embodiment.

The vapor phase growth apparatus according to this embodiment is avertical single-wafer-type epitaxial growth apparatus using a metalorganic chemical vapor deposition (MOCVD) method. The epitaxial growthapparatus according to this embodiment forms a group III-V nitride-basedsemiconductor single-crystal film, such as a gallium nitride (GaN) film,an aluminum nitride (AlN) film, an aluminum gallium nitride (AlGaN)film, or an indium gallium nitride (InGaN) film.

In FIG. 1, a vapor phase growth apparatus 1000 includes a reactionchamber 10. A film is grown in the reaction chamber 10.

The reaction chamber 10 includes a supporter 12 on which a wafer(substrate) W is placed and which rotates the wafer W in acircumferential direction of the wafer W. The wafer W is, for example, asilicon (Si) wafer or a sapphire wafer. For example, a holder which hasan opening at the center and supports the substrate on a circumferentialedge is used as the supporter 12. However, the supporter 12 may be asusceptor without an opening. In addition, the supporter 12 is providedwith, for example, a push-up pin (not illustrated) used to attach ordetach the wafer W to or from the supporter 12.

An upper end of a rotating shaft 18 is provided in the reaction chamber10. The supporter 12 is connected to the upper end of the rotating shaft18 through a rotating ring 14 and a rotating base 16 provided below therotating ring 14. The rotating shaft 18 is rotated by a rotatingmechanism 20 to rotate the wafer W in the circumferential direction.Here, the rotating mechanism 20 is not particularly limited. Forexample, a motor is used. The structures of the rotating ring 14, therotating base 16, and the rotating shaft 18 are not limited thereto.

A heater 26 is supplied with power by, for example, an external powersupply (not illustrated) through an electrode 22 that passes through theinside of the rotating shaft 18 and a current introduction terminal (notillustrated) and generates heat.

The reaction container 8 includes a wafer unloading/loading port (notillustrated). The wafer unloading/loading port is used to load the waferW into a reaction container 8 and to unload the wafer W from thereaction container 8. Here, for example, a robot hand (not illustrated)is used to load and unload the wafer W. The wafer W loaded by the robothand is supported by the supporter 12 in the reaction container 8. Amethod for loading and unloading the wafer W is not limited thereto.

The vapor phase growth apparatus 1000 includes a shower head 100provided above the reaction chamber 10. Here, the shower head 100includes a top plate 102, a mixing chamber 110, a shower plate 120, andan outer circumferential portion cooler 170.

The top plate 102 is provided above the mixing chamber 110 and includesa first manifold 152, a second manifold 154, a third manifold 156, afirst connection flow path 162, a second connection flow path 164, and athird connection flow path 166. A first process gas, a second processgas, and a third process gas are supplied from a first gas supply path142, a second gas supply path 144, and a third gas supply path 146 tothe first manifold 152, the second manifold 154, and the third manifold156, respectively. Then, the first process gas, the second process gas,and the third process gas are supplied to the mixing chamber 110 throughthe first connection flow path 162 connected to the first manifold 152,the second connection flow path 164 connected to the second manifold154, and the third connection flow path 166 connected to the thirdmanifold 156, respectively. The first process gas, the second processgas, and the third process gas are mixed in the mixing chamber 110.

For example, if a GaN single-crystal film is formed on the wafer W by anMOCVD method, hydrogen (H₂) is supplied as the first process gas. Inaddition, ammonia (NH₃), which is the source gas of nitrogen (N), issupplied as the second process gas. Furthermore, gas obtained bydiluting trimethylgallium (TMG) with H₂ is supplied as the third processgas. Here, TMG is the source gas of gallium (Ga), and H₂ is the carriergas.

The shower plate 120 is provided below the mixing chamber 110 andincludes a plurality of longitudinal flow paths 124 (124 a, 124 b, 124c, 124 d, 124 e, 124 f, 124 g, 124 h, 124 i, and 124 j) and lateralcooling flow paths 126 (126 a and 126 b) provided between thelongitudinal flow paths 124 c and 124 d and between the longitudinalflow paths 124 g and 124 h. A first cooling medium (cooling medium)flows through lateral cooling flow paths 126. Here, the shower plate 120is made of metal such as aluminum.

The first, second, and third process gases mixed in the mixing chamber110 flow through the longitudinal flow paths 124. The mixed gas of thefirst, second, and third process gases is supplied to the reactionchamber 10 and is used to grow a film on the wafer W. The surplusprocess gas and a by-product are exhausted from the reaction chamber 10by an exhaust device (not illustrated) through a gas exhaust portion 28provided in a lower part of the reaction chamber 10. Here, the exhaustdevice is, for example, a vacuum pump.

For example, the first cooling medium is supplied from a first chiller112 to the lateral cooling flow paths 126 and cools the shower head 100(shower plate 120). The first cooling medium may be supplied from thechiller to one (for example, the lateral cooling flow path 126 a) of thelateral cooling flow paths 126, may be supplied to the other lateralcooling flow path 126 (for example, the lateral cooling flow path 126b), and may be returned to the chiller. In addition, the first coolingmedium may be supplied from the chiller to a plurality of lateralcooling flow paths (126 a and 126 b) and may be returned to the chiller,without passing through other lateral cooling flow paths. Here, thefirst cooling medium is, for example, water. It is preferable that thelateral cooling flow path 126 have a straight shape for ease ofmanufacture, as illustrated in FIG. 2. However, the lateral cooling flowpath 126 may have some bent portions.

It is preferable that the diameter a of the lateral cooling flow path126, the diameter d of the longitudinal flow path 124, and the gap tbetween the plurality of longitudinal flow paths 124 satisfy thefollowing relationship in the plane perpendicular to the flow directionof the first cooling medium: d<t<a<d+2t. If the gap t between thelongitudinal flow paths 124 is equal to or less than the diameter d ofthe longitudinal flow path 124, the volume of a portion 120 a of theshower plate 120 which is adjacent to the longitudinal flow path 124 isreduced and the strength of the shower plate 120 is reduced, which isnot preferable. If the diameter a of the lateral cooling flow path 126is equal to or less than the gap t between the plurality of longitudinalflow paths 124, pressure loss increases and a sufficient amount of firstcooling medium does not flow through the lateral cooling flow path 126.Therefore, the shower head 100 (shower plate 120) is not sufficientlycooled. If the diameter a of the lateral cooling flow path 126 is equalto or greater than d+2t, the diameter of the lateral cooling flow path126 is large and it is difficult to provide many longitudinal flow paths124. As a result, reaction gas is not uniformly supplied onto the waferW and the non-uniformity of the thickness or composition of the filmformed on the wafer W increases.

It is preferable that the plurality of longitudinal flow paths 124 bedisposed at equal intervals in order to uniformly supply the reactiongas onto the wafer W in the plane perpendicular to the flow direction ofthe first cooling medium. However, the plurality of longitudinal flowpaths 124 are not necessarily disposed at equal intervals.

More preferably, the gap between the longitudinal flow path 124 g andthe longitudinal flow path 124 h that are provided adjacent to thelateral cooling flow path 126 b is d+2t in the plane perpendicular tothe flow direction of the first cooling medium. In other words, thewidth of the portion 120 a of the shower plate which is disposed betweenthe longitudinal flow path 124 g and the longitudinal flow path 124 h isd+2t in the plane perpendicular to the flow direction of the firstcooling medium. That is, another longitudinal flow path 124 can beprovided in the portion 120 a of the shower plate between thelongitudinal flow path 124 g and the longitudinal flow path 124 h,separating both from the longitudinal flow path 124 h and thelongitudinal flow path 124 i with the gap t. However, in thisembodiment, another longitudinal flow path 124 is not provided and thelateral cooling flow path 126 is provided.

Preferably, the cross-sectional shape of the lateral cooling flow path126 is a circle in the plane perpendicular to the flow direction of thefirst cooling medium in terms of ease of manufacture of the lateralcooling flow path 126. Preferably, the center of the cross section ofthe lateral cooling flow path 126 is equidistant from adjacentlongitudinal flow paths 124 g and 124 h in order to uniformly cool theshower head 100 (shower plate 120).

Preferably, the lateral cooling flow path 126 is disposed so as to beaway from the center 121 of the shower plate. In other words,preferably, the lateral cooling flow path 126 is not provided at thecenter 121 of the shower plate. In a single-wafer-type vapor phasegrowth apparatus, in general, the center of the wafer W is disposed on aline perpendicular to the center of the shower plate 120. In this case,in the structure in which the lateral cooling flow path 126 is disposedso as to be away from the center of the shower plate 120, because asmany longitudinal flow paths 124 as possible are provided at the centerof the shower plate 120 and the reaction gas is supplied, thedistribution of the reaction gas on the wafer W becomes uniform if thewafer W is rotated in the circumferential direction of the wafer W.

It is preferable that a plurality of lateral cooling flow paths 126 besymmetrically provided with respect to the center 121 of the showerplate in order to uniformly cool the shower head 100.

The outer circumferential portion cooler 170 includes an outercircumferential portion cooling flow path 172 and an outercircumferential portion pipe 174. The outer circumferential portioncooling flow path 172 is provided around the shower plate 120. In thisembodiment, for example, a second cooling medium is supplied from asecond chiller 114 to the outer circumferential portion cooling flowpath 172 through the outer circumferential portion pipe 174 to cool theshower head 100 (shower plate 120). Here, the second cooling medium is,for example, water. The outer circumferential portion pipe 174 isdisposed on the upper side of the plane of paper in FIG. 2. However, theposition where the outer circumferential portion pipe 174 is disposed isnot particularly limited. The outer circumferential portion cooler isnot limited thereto. For example, a known cooling mechanism, such as acooling fin provided around the shower plate 120, may be preferablyused.

It is preferable that the difference between the temperature of theoutermost circumferential portion of the shower plate 120 and thetemperature of the center 121 of the shower plate be equal to or lessthan 5° C. In this case, it is possible to control the thickness orcomposition of a film formed on the wafer W so as to be uniform, whichwill be described below. Here, the temperature of the outermostcircumferential portion of the shower plate 120 is defined as thetemperature of a portion of the shower plate 120 adjacent to alongitudinal flow path 124 which is provided at the outermostcircumference of the shower plate 120 among the longitudinal flow paths124. If the longitudinal flow path 124 is provided at the center 121 ofthe shower plate, the temperature of a wall surface of the longitudinalflow path 124 is measured and the measured temperature can be used asthe temperature of the center 121 of the shower plate. Otherwise, thetemperature of a portion of the shower plate 120 adjacent to thelongitudinal flow path 124 provided at the center 121 of the showerplate may be measured, and the measured temperature may be used as thetemperature of the center 121 of the shower plate. Here, the temperatureof the shower plate 120 is preferably measured by, for example, athermocouple or a radiation thermometer.

A controller 180 is connected to the rotating mechanism 20, the heater26, the exhaust device, and the outer circumferential portion cooler 170by wires (not illustrated). In addition, the controller 180 is connectedto the first chiller 112 and the second chiller 114. The controller 180performs an operation of controlling the rotation of the wafer W by therotating mechanism 20 and the rotation speed of the wafer W, anoperation of controlling the heating of the wafer W by the heater 26, anoperation of controlling the supply of the process gas from the firstgas supply path 142, the second gas supply path 144, and the third gassupply path 146 to the reaction chamber 10, an operation of controllingthe transport of the wafer W by the robot hand, an operation ofcontrolling the exhaust of the surplus process gas and a by-product fromthe gas exhaust portion by the exhaust device, an operation ofcontrolling the temperature of the shower plate 120 using the firstchiller 112 and the lateral cooling flow path 126, and an operation ofcontrolling the temperature of the shower plate 120 using the secondchiller 114 and the outer circumferential portion cooling flow path 172.

The controller 180 may compose of hardware such as an electrical circuitor a quantum circuit, or may compose of software. If the controller 180may compose of software, a microprocessor centered on a centralprocessing unit (CPU), a read only memory (ROM) that stores a processingprogram, a random access memory (RAM) that temporarily stores data, aninput/output port, and a communication port may be used. A recordingmedia may not be limited to detachable disks such as magnetic disk oroptical disk, and fixed recording media such as hard disk device ormemory may also be preferable.

FIG. 3 is a bottom view schematically illustrating a shower plate and anouter circumferential portion cooling flow path of a vapor phase growthapparatus according to another aspect of the first embodiment. Theshower head 100 illustrated in FIG. 2 is provided with two lateralcooling flow paths, that is, the lateral cooling flow path 126 a and thelateral cooling flow path 126 b. However, four cooling flow paths may besymmetrically provided with respect to the center 121 of the showerplate such that two cooling flow paths are disposed on one side of thecenter 121.

FIG. 4 is a flowchart illustrating a vapor phase growth method accordingto this embodiment.

First, the controller 180 loads the wafer W into the reaction chamber 10and places the wafer W on the supporter 12, using, for example, therobot hand. Then, the controller 180 heats the wafer W using the heater26. Then, the controller 180 rotates the wafer W in the circumferentialdirection of the wafer W at a predetermined rotation speed, using therotating mechanism 20.

Then, the controller 180 supplies the first process gas, the secondprocess gas, and the third process gas from the first gas supply path142, the second gas supply path 144, and the third gas supply path 146to the mixing chamber 110 and mixes the first process gas, the secondprocess gas, and the third process gas (S10). Among the first processgas, the second process gas, and the third process gas, two types ofprocess gas may be mixed.

Then, the controller 180 supplies the first process gas, the secondprocess gas, and the third process gas mixed in the mixing chamber 110to the longitudinal flow paths 124 provided in the shower plate 120(S12).

Then, the controller 180 controls the temperature of the shower plate120, using the lateral cooling flow paths 126 and the outercircumferential portion cooling flow path 172, such that the differencebetween the temperature of the outermost circumferential portion and thetemperature of the central portion in the shower plate 120 is equal toor less than 5° C. (S14).

Then, the mixed gas of the first process gas, the second process gas,and the third process gas supplied to the longitudinal flow paths 124 issupplied to the reaction chamber (S16).

Then, a film is grown on the wafer W placed on the supporter 12 in thereaction chamber 10, using the first process gas, the second processgas, and the third process gas (S18).

After the growth of the film is completed, the temperature of the waferW is reduced and the wafer W is unloaded from the reaction container 8,using, for example, the robot hand.

FIGS. 5A and 5B illustrate the temperature distribution of the showerplate 120 in this embodiment. FIG. 5A illustrates the temperaturedistribution of the shower plate 120 when the shower plate 120 is cooledby the lateral cooling flow path 126, without using the outercircumferential portion cooling flow path 172, and FIG. 5B illustratesthe temperature distribution of the shower plate 120 when the showerplate 120 is cooled by both the outer circumferential portion coolingflow path 172 and the lateral cooling flow path 126.

In FIG. 5A, the temperature of a portion of the shower plate 120 (thecenter 121 of the shower plate) above the center of the wafer W is 85°C. and the temperature of a portion of the shower plate 120 that is 75mm away from the center of the wafer W is 75° C. Therefore, thedifference between the temperature of a portion of the shower plate 120above the center of the wafer W (the center 121 of the shower plate) andthe temperature of a portion of the shower plate 120 that is 75 mm awayfrom the center of the wafer W is 10° C.

On the other hand, in FIG. 5B, the temperature of a portion of theshower plate 120 above the center of the wafer W (the center 121 of theshower plate) is 70° C. and the temperature of a portion of the showerplate 120 that is 75 mm away from the center of the wafer W is 65° C.Therefore, the difference between the temperature of a portion of theshower plate 120 (the center 121 of the shower plate) above the centerof the wafer W and the temperature of a portion of the shower plate 120that is 75 mm away from the center of the wafer W is 5° C.

FIGS. 6A to 6D are diagrams illustrating the characteristics of a filmformed by the vapor phase growth apparatus according to this embodiment.FIG. 6A illustrates the dependence of the thickness of a film (period),which is formed while the shower plate 120 is cooled by the lateralcooling flow path 126, without using the outer circumferential portioncooling flow path 172, on a position in the plane of the wafer W. FIG.6B illustrates the dependence of the Al composition distribution of afilm, which is formed while the shower plate 120 is cooled by thelateral cooling flow path 126, without using the outer circumferentialportion cooling flow path 172, on a position in the plane of the waferW. FIG. 6C illustrates the dependence of the thickness of a film(period), which is formed while the shower plate 120 is cooled by boththe outer circumferential portion cooling flow path 172 and the lateralcooling flow path 126, on a position in the plane of the wafer W. FIG.6D illustrates the dependence of the Al composition distribution of afilm, which is formed while the shower plate 120 is cooled by both theouter circumferential portion cooling flow path 172 and the lateralcooling flow path 126, on a position in the plane of the wafer W.

When cooling is performed by the lateral cooling flow path 126, withoutusing the outer circumferential portion cooling flow path 172, thedifference between the thickness of the film on the center of the waferW and the thickness of the film on a portion of the wafer W that is 75mm away from the center is ±3%, as illustrated in FIG. 6A. In contrast,when cooling is performed by both the outer circumferential portioncooling flow path 172 and the lateral cooling flow path 126, thedifference between the thickness of the film on the center of the waferW and the thickness of the film on a portion of the wafer W that is 75mm away from the center is ±1%, as illustrated in FIG. 6C.

In FIG. 6A, the thickness of the film on the center (0 mm) of the waferW is the largest and the thickness of the film on the periphery of thewafer W is the smallest. The difference between the thickness of thefilm on the center of the wafer W and the thickness of the film on aportion of the wafer W that is 95 mm away from the center is ±3%. InFIG. 6C, the difference between the thicknesses is reduced to ±1%. InFIG. 6B, the difference between the Al concentrations is ±2%. In FIG.6D, the difference between the Al concentrations is reduced to ±0.6%.This shows that, when the shower head is uniformly cooled, thecharacteristics of a formed film, such as the thickness of the film andthe element concentration of the film, are improved.

According to the shower head, the vapor phase growth apparatus, and thevapor phase growth method of this embodiment, since the shower head isuniformly cooled, it is possible to form a film with a uniformthickness.

Second Embodiment

A shower head according to this embodiment differs from the shower headaccording to the first embodiment in that it further includes a firsttransparent member 128 provided between the longitudinal flow paths, asecond transparent member 130 provided in the top plate 102, and ameasuring instrument provided on the second transparent member 130.Here, the description of the same components as those in the firstembodiment will not be repeated.

FIG. 7 is a diagram schematically illustrating a main portion of a vaporphase growth apparatus according to this embodiment. FIG. 8 is a bottomview schematically illustrating a shower plate and an outercircumferential portion cooler of the vapor phase growth apparatusaccording to this embodiment.

The first transparent member 128 (128 a and 128 b) is provided betweenthe longitudinal flow path 124 e and the longitudinal flow path 124 f.The second transparent member 130 is provided in the top plate 102.

A measuring instrument 50 is provided on the top plate 102. Themeasuring instrument 50 is, for example, an instrument that measures thewarping of the wafer W using a laser, a device that measures thethickness or quality of a film grown on the wafer W using a laser, or aradiation thermometer that measures the temperature of the wafer W usingradiation from the wafer W. The first transparent member 128 and thesecond transparent member 130 pass through the shower plate 120 and thetop plate 102, respectively, in order to effectively irradiate the waferW with laser beams and detect reflected laser beams, or to effectivelydetect the radiation. The second transparent member 130 is disposedright above the first transparent member 128 and the measuringinstrument 50 is disposed right on the second transparent member 130.

The first transparent member 128 and the second transparent member 130are sufficiently transparent with respect to a predetermined wavelengthused in the measuring instrument 50 and are preferably, for example,quartz glass. Any member may be used as long as it has sufficientlystrength, is sufficiently transparent with respect to a predeterminedwavelength, and has high resistance to, for example, process gas. Forexample, sapphire can be preferably used.

In FIG. 8, the first transparent members 128 a and 128 b have arectangular shape in which a long side is parallel to the direction ofthe lateral cooling flow path 126 in which the first cooling mediumflows. However, the first transparent members 128 a and 128 b may have arectangular shape in which a long side is perpendicular to the flowdirection of the first cooling medium.

FIG. 9 is a bottom view schematically illustrating a shower plate and anouter circumferential portion cooler of a vapor phase growth apparatusaccording to another aspect of this embodiment. First transparentmembers 128 a, 128 b and 128 c may have a rectangular shape in which along side is perpendicular to the flow direction of the first coolingmedium.

FIG. 10 is a bottom view schematically illustrating a shower plate andan outer circumferential portion cooler of a vapor phase growthapparatus according to another aspect of this embodiment. Thelongitudinal flow paths 124 may be arranged such that the outlets of thelongitudinal flow paths 124 are parallel to a long side of the firsttransparent member 128, as illustrated in FIGS. 8 and 9, or may bearranged such that the outlets of the longitudinal flow paths 124 areinclined at 45 degrees with respect to a long side of the firsttransparent member 128, as illustrated in FIG. 10.

According to the shower head, the vapor phase growth apparatus, and thevapor phase growth method of this embodiment, it is possible to formafilm with a uniform thickness, similarly to the first embodiment. Inaddition, according to the shower head, the vapor phase growthapparatus, and the vapor phase growth method of this embodiment, it ispossible to observe the state of the wafer W while a film is beingformed. Therefore, the controllability of the temperature or warping ofthe wafer W while a film is being formed is improved.

Third Embodiment

A shower head according to this embodiment differs from the shower headaccording to the second embodiment in that the longitudinal flow path124 is provided in the first transparent member 128. Here, thedescription of the same components as those in the second embodimentwill not be repeated.

FIG. 11 is a bottom view schematically illustrating a shower plate andan outer circumferential portion cooler of a vapor phase growthapparatus according to this embodiment. If the longitudinal flow path124 is provided in the first transparent member 128, it is possible touse a large transparent member. Therefore, for example, it is possibleto measure temperature at a large number of positions on the surface ofthe wafer W, using a large number of radiation thermometers. Inaddition, it is possible to measure the warping of the wafer W indetail, using, for example, a device that measures the warping of thewafer W at a large number of positions. As a result, the controllabilityof the temperature or warping of the wafer W while a film is beingformed is improved.

According to the shower head, the vapor phase growth apparatus, and thevapor phase growth method of this embodiment, it is possible to formafilm with a uniform thickness, similarly to the first embodiment. Inaddition, the controllability of the temperature or warping of the waferW while a film is being formed is improved. It is possible to measurevarious states of the wafer W.

Fourth Embodiment

In this embodiment, the vapor phase growth apparatus according to anyone of the first to third embodiments is used. However, this embodimentdiffers from the first to third embodiments in that the temperature ofthe shower head 100 (shower plate 120) varies depending on the film tobe grown. Here, the description of the same components as those in thefirst to third embodiments will not be repeated.

FIG. 12 is a flowchart illustrating a vapor phase growth methodaccording to the fourth embodiment.

First, the wafer W is heated to a predetermined temperature and thecontroller 180 controls the first chiller 112 connected to the lateralcooling flow path 126 and the second chiller 114 connected to the outercircumferential portion cooling flow path 172 such that the temperatureof the shower head 100 is, for example, 60° C. Then, for example,hydrogen (H₂), ammonia (NH₃), and trimethylaluminum (TMA) are suppliedto grow an AlN film on the wafer W (S30).

Then, the temperature of the shower head 100 is set to 90° C. and, forexample, hydrogen, ammonia, and trimethylgallium (TMG) are supplied toform a GaN film on the wafer W (S32).

Then, a multiple quantum well (MQW) layer is formed on the GaN film(S34). Then, the temperature of the shower head 100 is set to 90° C.and, for example, hydrogen, ammonia, TMG, TMA, and Cp₂Mg(bis(cyclopentadienyl)magnesium) are supplied to grow a p-AlGaN filmdoped with Mg (S36).

As such, since the temperature of the shower head 100 varies dependingon the film to be formed, it is possible to obtain a film with highcrystallinity at a high growth speed.

In this embodiment, when an AlN film is formed, the temperature of theshower head 100 is 60° C. However, the temperature of the shower head100 is preferably equal to or greater than 40° C. and equal to or lessthan 80° C. and more preferably equal to or greater than 50° C. and isequal to or less than 70° C.

In addition, when a GaN film and a p-AlGaN film are formed, thetemperature of the shower head 100 is 90° C. However, when a filmincluding Ga or Mg other than a simple AlN film is formed, thetemperature of the shower head 100 is preferably equal to or greaterthan 70° C. and equal to or less than 130° C., which is higher than thatwhen the AlN film is formed. The temperature of the shower head 100 ismore preferably equal to or greater than 80° C. and equal to or lessthan 90° C.

The vapor phase growth method according to this embodiment does notnecessarily use the vapor phase growth apparatus according to any one ofthe first to third embodiments and the invention is not limited thereto.

In the above-described embodiments, for example, portions which are notnecessary to describe the invention, such as structures, are notdescribed. However, for example, necessary structures can beappropriately selected and used. In addition, the shower heads, thevapor phase growth apparatuses, and the vapor phase growth methods whichinclude the components according to the invention and whose design canbe appropriately changed by those skilled in the art are included in thescope of the invention. The scope of the invention is defined by thescope of the claims and the scope of equivalents thereof.

What is claimed is:
 1. A shower head comprising: a mixing chamber mixinga plurality of process gases; a shower plate provided below the mixingchamber, the shower plate including a plurality of longitudinal flowpaths and a lateral cooling flow path provided between the longitudinalflow paths, a mixed gas of the process gases flowing through thelongitudinal flow paths, a cooling medium flowing through the lateralcooling flow path, the shower plate further including a firsttransparent member provided between at least two of the longitudinalflow paths; an outer circumferential portion cooling flow path providedaround the shower plate; a top plate provided above the mixing chamber;a second transparent member passing through the top plate; and ameasuring instrument provided on the second transparent member.
 2. Theshower head according to claim 1, wherein a diameter a of the lateralcooling flow path, a diameter d of the longitudinal flow path, and a gapt between the longitudinal flow paths satisfy t<a<d+2t in a planeperpendicular to a flow direction of the cooling medium.
 3. The showerhead according to claim 1, wherein a gap between the longitudinal flowpaths provided adjacent to the lateral cooling flow path is d+2t.
 4. Theshower head according to claim 1, wherein the lateral cooling flow pathis separately disposed from a center of the shower plate.
 5. The showerhead according to claim 1, wherein a difference between the temperatureof an outermost circumferential portion and the temperature of a centralportion of the shower plate is equal to or less than 5° C.
 6. A vaporphase growth apparatus comprising: a reaction chamber; a supporterprovided in the reaction chamber, a substrate being capable of beingplaced on the supporter; and a shower head provided in an upper part ofthe reaction chamber, the shower head including a mixing chamber mixinga plurality of process gases, a shower plate provided below the mixingchamber, the shower plate including a plurality of longitudinal flowpaths and a lateral cooling flow path provided between the longitudinalflow paths, a mixed gas of the process gases flowing through thelongitudinal flow paths, a cooling medium flowing through the lateralcooling flow path, the shower plate further including a firsttransparent member provided between at least two of the longitudinalflow paths, an outer circumferential portion cooling flow path providedaround the shower plate, a top plate provided above the mixing chamber,a second transparent member passing through the top plate, and ameasuring instrument provided on the second transparent member.
 7. Thevapor phase growth apparatus according to claim 6, wherein a diameter aof the lateral cooling flow path, a diameter d of the longitudinal flowpath, and a gap t between the longitudinal flow paths satisfy t<a<d+2tin a plane perpendicular to a flow direction of the cooling medium. 8.The vapor phase growth apparatus according to claim 6, wherein a gapbetween the longitudinal flow paths provided adjacent to the lateralcooling flow path is d+2t.
 9. The vapor phase growth apparatus accordingto claim 6, wherein the lateral cooling flow path is separately disposedfrom a center of the shower plate.
 10. The vapor phase growth apparatusaccording to claim 6, wherein a difference between the temperature of anoutermost circumferential portion and the temperature of a centralportion of the shower plate is equal to or less than 5° C.
 11. The vaporphase growth apparatus according to claim 6, further comprising: acontroller controlling a temperature of the shower plate using thelateral cooling flow paths and the outer circumferential portion coolingflow path.
 12. The shower head according to claim 1, wherein some of thelongitudinal flow paths are provided in the first transparent member.13. The shower head according to claim 12, wherein a diameter a of thelateral cooling flow path, a diameter d of each of the longitudinal flowpaths, and a gap t between the longitudinal flow paths satisfy t<a<d+2tin a plane perpendicular to a flow direction of the cooling medium. 14.The vapor phase growth apparatus according to claim 6, wherein some ofthe longitudinal flow paths are provided in the first transparentmember.
 15. The shower head according to claim 1, wherein the firsttransparent member and the second transparent member are arranged sothat the measuring instrument is optically accessible through the firsttransparent member and the second transparent member.
 16. The vaporphase growth apparatus according to claim 6, wherein the firsttransparent member and the second transparent member are arranged sothat the measuring instrument is optically accessible to the substratethrough the first transparent member and the second transparent member.